Tapered setting wedge for swell packers and associated method

ABSTRACT

A swell packer sealing element has a wedge on either or both ends that is driven axially when the packer is at the desired borehole location. The wedge releases an end bond of the sealing element and forces the end of the sealing element out radially against the surrounding borehole wall. The actuator for the wedge also forces out an extrusion barrier at the same time. The packer achieves the ability to handle the design differential pressure with aid of the end wedge even as portions of the packer sealing element beyond the end are still swelling into contact with the surrounding borehole wall whether in cased or open hole.

FIELD OF THE INVENTION

The field of the invention is swelling packers for borehole use and more particularly where the sealing element is wedged on at least one end to radially compress the sealing element by advancing between a mandrel and the sealing element.

BACKGROUND OF THE INVENTION

Borehole barriers are deployed for zone isolation for a variety of reasons. These barriers come on many configurations with some of the more popular styles being compression set and swell packers. Compression set packers employ tubing pressure to move a piston to axially compress a sealing element to a set position. There are other actuation modes by axial compression but in essence the sealing element that is an elastomer sleeve has its ends pushed together and the radius increases as a result until contact with a surrounding borehole is made for the set position.

Swell packers grow radially by exposure to well fluids already present, as in U.S. Pat. No. 9,587,459 FIGS. 4A-4B, or added to the borehole or by thermal loading from well temperatures. As a result of the swelling, the diameter of a sealing element grows into contact with the surrounding borehole wall for the set position. Sometimes the sealing element is covered with a sheath that goes away with exposure to well fluids in an effort to delay the onset of swelling until the desired depth is reached, as shown in US 2009/0178800. Typically the swelling element is boded to a supporting mandrel. One issue with such packers is that they take too long to fully set and even when fully swelled still have issues with holding the needed differential pressures.

Several attempts have been made to combine the swelling action with applied forces to ensure the desired performance of the swelling element in the set position. WO2017/058191 FIG. 4 illustrates the use of overlapping leaf structures on an end of a swelling element and an actuator that contacts the element during the set. The tool is in rotational registry with the end leaves on the sealing element. In essence the swelling element is end compressed and allowed to swell. A similar design that uses end compression of a swelling element 250 with a pressure actuated piston 242 powered by tubing pressure is EP 2407632, FIGS. 4A-4D. Another design combines a swell packer with a compression set packer where only the compression set packer is axially compressed, as in FIGS. 7 and 8 of U.S. Pat. No. 8,251,142 and a similar design in US 2012/0012342.

The present design addresses issues with prior designs with an end wedge that cooperates with an extrusion barrier where the wedge has a ramp surface pointing into the sealing element to separate the bond to the underlying mandrel and to add a radial force component to the end of the sealing element to allow the sealing element to come to design resistance to differential pressure sooner. The end wedge also interacts with the extrusion barrier to force the extrusion barrier out radially as the sealing element end is forced out radially making the swell packer almost immediately available for service upon wedge actuation even as the sealing element continues to swell to its final position against the surrounding borehole wall whether in open or cased hole.

SUMMARY OF THE INVENTION

A swell packer sealing element has a wedge on either or both ends that is driven axially when the packer is at the desired borehole location. The wedge releases an end bond of the sealing element and forces the end of the sealing element out radially against the surrounding borehole wall. The actuator for the wedge also forces out an extrusion barrier at the same time. The packer achieves the ability to handle the design differential pressure with aid of the end wedge even as portions of the packer sealing element beyond the end are still swelling into contact with the surrounding borehole wall whether in cased or open hole.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a section view of the swell packer in the run in position;

FIG. 2 is the packer of FIG. 1 in the set position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1 the swell packer 10 has a mandrel 12 and a swelling sealing element 14. Typically the element 14 is bonded to the mandrel 12 and can be in the order of 10 meters long or more. A setting piston 16 is held for run in by shear pin 18. A port 20 leads to sealed chamber 22 that is sealed with seal 24 and 26. Tubing pressure in passage 2 enters chamber 22 and increases its volume as shear pin 18 is broken and piston 16 moves toward the sealing element 14. Such movement is locked with a ratcheting lock ring 30. Piston 16 has a leading taper 32 that aligns with taper 34 of anti-extrusion ring 36. Ring 36 has a taper 38 opposite taper 34 to engage taper 40 of wedge 42. The cross-sectional shape of anti-extrusion ring 36 can be triangular or trapezoidal and movement of the piston 16 forces anti-extrusion ring 36 out toward the borehole wall 44, which can be cased or open hole.

Wedge 42 has a leading taper 46 which is preferably about 3 degrees but can be a greater or lesser angle that still ensures that end 48 slides between mandrel 12 and end 50 of the sealing element 14 as shown in FIG. 2 as a result of movement of piston 16. Piston 16 although shown as actuated with tubing pressure from passage 28 can also be translated in other ways such as with a setting tool that causes differential part movement as between the piston 14 and the mandrel 16.

While the element 14 will swell when exposed to the swelling stimulus in the known way, the leading taper 46 will break the bond against the mandrel 12 and push end 50 radially outwardly against the borehole wall 44. What this does is provide immediate end isolation capability as end 50 is separated from the mandrel 12 and radially compressed against the borehole 44. This can happen as other parts of sealing element 14 have not fully swelled against the borehole wall 44. The packer is not only ready for the designed pressure differential that much sooner but the radial end force enhances the capability of the packer to resist pressure differential at an earlier time and does not create a leak path along the mandrel 12 if the radial boost force was to be applied along the full length of the sealing element 14. The illustrated arrangement can be present at the taphole end of the packer 10 only if the differential pressure is applied from above or on opposed ends if the differential can be in either of opposed directions.

The packer 10 can be used in well treatment into the formation. The teachings of the present disclosure may be used in a variety of well operations. These operations may involve using one or more treatment agents to treat a formation, the fluids resident in a formation, a wellbore, and/or equipment in the wellbore, such as production tubing. The treatment agents may he in the form of liquids, gases, solids, semi-solids, and mixtures thereof. Illustrative treatment agents include, but are not limited to, fracturing fluids, acids, steam, water, brine, anti-corrosion agents, cement, permeability modifiers, drilling muds, emulsifiers, demulsifiers, tracers, flow improvers etc. Illustrative well operations include, but are not limited to, hydraulic fracturing, stimulation, tracer injection, cleaning, acidizing, steam injection, water flooding, cementing, etc.

The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below: 

I claim:
 1. A swell packer assembly for borehole use, comprising: a mandrel; a swelling element mounted to said mandrel having an end; a selectively movable wedge on said mandrel movable past said end into a position between said mandrel and said end to force said end toward a surrounding borehole wall.
 2. The assembly of claim 1, wherein: said element at a location beyond said wedge remains in contact with said mandrel.
 3. The assembly of claim 2, wherein: said swelling element initially bonded to said mandrel and said movable wedge releasing said bond as a result of said selective movement.
 4. The assembly of claim 2, wherein: movement of said movable wedge extends an anti-extrusion ring radially toward the surrounding borehole wall.
 5. The assembly of claim 2, wherein: said movable wedge has a taper angle of about 3 degrees.
 6. The assembly of claim 1, wherein: said swelling element is not fully in contact along the length of said swelling element when said movable wedge advances said end radially into the borehole wall.
 7. The assembly of claim 1, wherein: said sealing element forms a differential pressure seal against the borehole at said end from advancement of said movable wedge.
 8. The assembly of claim 1, wherein: said wedge is moved with tubing passage pressure.
 9. The assembly of claim 1, wherein: said movable wedge is locked against reverse movement after movement toward said sealing element.
 10. The assembly of claim 4, wherein: said anti-extrusion ring is located on said mandrel between an actuating piston and said movable wedge.
 11. The assembly of claim 10, wherein: said piston is moved with tubing passage pressure.
 12. The assembly of claim 11, wherein: a lock ring prevents reverse movement of said piston after initial movement toward said end of said sealing element.
 13. A borehole treatment method, comprising: sealing a borehole with a swelling element mounted to a mandrel; advancing a wedge past an end of said swelling element along said mandrel; forcing said end of said swelling element away from said mandrel and toward a borehole wall with said wedge; isolating one zone from another zone in the borehole from said sealing.
 14. The method of claim 13, comprising: performing a well treatment in one of said zones.
 15. The method of claim 14, comprising: providing as said treatment at least one of hydraulic fracturing, stimulation, tracer injection, cleaning, acidizing, steam injection, water flooding and cementing.
 16. The method of claim 13, comprising: breaking a bond between said sealing element and said mandrel with said wedge advancing.
 17. The method of claim 13, comprising: radially forcing said end away from said mandrel and toward the borehole wall with said advancing of said wedge.
 18. The method of claim 13, comprising: applying differential pressure to said end before the substantial length of said swelling element has swelled into contact with the borehole wall.
 19. The method of claim 13, comprising: extending an anti-extrusion ring with said advancing of said wedge.
 20. The method of claim 13, comprising: disposing an anti-extrusion ring on said mandrel between a piston and said wedge; driving said wedge axially past said end and said anti-extrusion ring radially toward the borehole wall with piston movement using tubing passage pressure.
 21. The method of claim 20, comprising: locking reverse movement of said piston after said driving of said wedge; disposing said swelling element in contact with said mandrel along its substantial length beyond a shifted position of said wedge. 